Pressure controlled switch



. May 29, 1934. L, A. LEMAITRE ET AL PRESSURE CONTROLLED SWITCH Filed Feb. l0, 1932 3o vehicle.

Patented May 29 .1934" UNITED, STATES PATENT OFFICE 1,961,004 PRESSURE coNTRoLLED swrrclr Leon A. Lematre andJoseph Rassas, Long Branch, N. J.

Application February 10, 1932, Serial No. 592,110

/ Z'ClaimS. (Cl. 200-82) 1 10 the oil pump fails).

Also to delay the lclosing :of' the circuit untill the 4engine gains sufficient speed toprevent back firing when hand cranking is resorted to, which often results in serious injury to the operator.

Itis desirable, when the oil supply is exhausted 1 or the oil pump fails to function, to break the circuit through the ignition plugs of the engine .s

as damage mayfresult to the bearings or other parts thereof from the failure of the pump to supply lubricant thereto. y

With these and other objects more fully set forthv i'n the following specification, defined in" the appended claims and illustrated in the accompanying drawing in which: V-

Fig. 1 is a vertical section through the device;

Fig. 2 a section on line 2-2 of Fig. l.

In the drawing a cylinder 7 is connected. by means of a pipe 5 to the usual oil pressure gauge mounted on the instrument board of a motor A piston 6 is loosely mounted in the cylinder to permit a leakage between it and the wall of the cylinder and has secured thereto a rod 8 which projects through an opening 20 in the cylinder closure 9. By spacing the piston from'the cylinder wall the oil that escapes past the piston. forms a fllm of lubricant around the piston head which reduces friction and provides for a more sensitive operation of the device. To further reduce friction in the operation of the piston, the opening 20 is of suicient area to permity the piston rod to slide freely therethrough.

To prevent the escape of oil that has leaked past the piston through the opening 20, an opening 21 is formed in theiower part of the cyl-4 l the switch box and carries a conductor' 14 insurearwardly whereby the head 10 on the piston ply, a spring 13 secured to the base 22'and bearlated therefrom which is adapted to bridge contacts 15 interposed'in the ignition circuit and secured to non-conducting supports 25 mounted within' the switch housing.

When the engine starter is set in operation or the engine is cranked manually, the oil pump forces oil under pressure through the lubricating system thus creating a pressure in the pipe 5 against the head of the piston 6 which moves r'od after a slight movement engages the head 26 on the switch Arod 11 and moves the rod and conductor 14 to bridge the contacts 15. This operation completes the ignition circuit whereupon the engine starts to operate and continues to do so as long as the oil pump creates apressure in the lubricatingsystem.

When the oil pressure fails, due to the failure of the oil pump or the exhaustion of the oil suping ,against the Aopposite end of the switch rod,

moves it forwardly to disengage the conductor from the contacts 15 and break the circuit whereupon the engine ceases to operate.

The switch is preferably interposed between the ignition coil and the distributor and forms an. effective means for holding the circuit open.

while the engine is idle, even though the usual enough pressure is built up in the cylinder to cause the piston to close the circuit. As it is necessary, therefore, forthe engine to attain a' certain speed before the circuit is closed through the ignition plugs there is less danger of backring. Thisconstruction obviates the necessity of packing the piston orV piston rod whichl permits a more sensitive operation of the device.

By providing 'a spacebetween the piston rod andswitch rod the piston has' gained sunicient momentum by the time it engages -the switch rod to cause a rapid closing of the switch which prevents arcing and reduces to a minimum the danger of fire.

'I'he switch housing is spaced from the cylinder and its related elements so that oil in the cylinder is prevented from entering the housing thereby foulingthe contacts and -constituting a serious fire hazard.

In effect the space between the cylinder and piston is normally sealed by the oil and the pis ton is practically suspended by the escaping oil.

sli

Having described our invention and set forth its merits, what we claim is: f

1. A liuidl actuated switchl operating mecha-` nisxn, comprising a cylinder, a piston in said cylinder, a piston rod secured to the piston and positioned to engage a,switch member spaced from said cylinder; said cylinder having a pres? sure inlet at one end and a discharge port at the opposite end, the piston being positioned be- -tween the inlet and discharge ports oi' the cylinder, and peripherally spaced from the cylinder 'wallsuiciently to permit a constant proportional discharge 'of fluid `past the piston to control operation oi.' the. switch.

2.a guia actuated switch operating mecha-- nism, comprising a cylinder, a piston'insaid cylindex', ya piston rod secured to the piston` 'and tional discharge of fluid past the piston, saidH piston rod passing .freely through the end wall 4oi.' the cylinder to lessen frictional contact between the end wall and piston rod. l

. LEON A.l LEMAIIRE.

f JOSEPH RASSAS.

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